Comparing with an SLC (Single-Level Cell) Nand Flash, an MLC (Multi-Level Cell) Nand Flash has a higher storage density and has been used more widely in the field of solid-state hard disks. In one memory cell of an MLC Nand Flash, 2 bits of information can stored. The 2 bits belong to two different pages, respectively. Such a pair of pages is called as couple pages, of which a page for storing a low bit is called as a low page and the other page for storing a high bit is called as an up page. The couple pages are subjected to two constraints as follows during a process of writing: 1) the low page must be written before the up page is written; and 2) if the writing to the up page is interrupted by, for example, abnormal power down during the process of writing, information on the up page will be lost and information on the corresponding low page may also be lost, but the low page will not affect the corresponding up page.
As a solution, the prior art additionally provides a standby power supply or super capacitor to enable the data, which is currently being written, to be successfully written to a Nand Flash when a main power supply is down. However, this solution requires the provision of an external hardware support, increasing the cost and complexity of hardware.
To sum up, the existing methods of writing data to a solid-state storage system is obviously inconvenient and deficient in an practical application thereof, thus it is necessary to to make an improvement.